Rotor assemblies comprising two or more rotor blades may be found in a wide range of rotary or fixed wing aircrafts vehicles, including UAVs, that may employ one or more rotor assemblies. Rotary wing aircrafts, such as helicopter or quadcopters, are sustained by rotors rotating about a vertical axis, generating lift or upward thrust. Fixed wing aircrafts, on the other hand, utilize horizontally oriented rotor assemblies to generate forward thrust.
Traditionally, the rotors used in these aircrafts have been simple plastic parts, and the rotors are fixed to the rotor shaft with a screw or nut arrangement. For example, the rotor shaft may comprise threads, and a hole in the center of the rotor is positioned on the shaft and attached by a nut fixing it in place. However, due to maintenance, to optimize performance or to alter the characteristics of the rotor, it is often necessary to change to a new rotor. Which, with a screw mounted rotor would take an unnecessary long time. The fixed connection could also mean that the rotor may damage other parts of the aircraft if it is to come in contact with something. If the aircraft experience a more severe crash, the fixed connection may have the consequence that the rotor blades and several of the connecting parts are damaged and must be replaced. In addition, the rotors of modern aircrafts, as e.g. UAVs, may comprise complicated parts and designs, making it undesirable and costly to simply replace the rotor at each contact with an object.
A slight improvement is provided by rotors were the rotor blades can swing back and forth about a single mounting screw positioned in the inner part of the blades, close to the rotor shaft. If the blades hit an object while the rotor spins this can help reduce the damage to the blades and to the rest of the aircraft. However, even if the blades are free to swing in one plane they are often damaged by the slightest contact with an obstacle. Usually also affecting the hub and the rotor shaft.
WO2010114387 presents a future improvement where a rotor assembly may be attached using magnets, positioning and retaining the rotor assembly during use. However, the solution is complex, and the magnets should be large to account for all forces experienced during flight. Using large magnets may then affect the onboard sensors used for navigation in a modern-day aircraft as well as attracting magnetic particles. This again complicates maintenance and could imply misalignment and a lower performance of the rotor if not regularly maintained.
Therefore, there is a need for a system that allows for an easy positioning and replacement of a rotor assembly, still addressing the requirements of modern day aircrafts and UAVs. Such a system could also disconnect the rotor from the aircraft in the event of a crash, avoiding time consuming and expensive repairs. Further, the system could even be used to remove the rotor from the aircraft for storage and allow for easier transportation of an aircraft.